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  • Open Access


    Characterizing the Ultra-Slow Creep in Concrete Based on the Non-Local Structural Derivative Maxwell Model

    Xianglong Su*, Wenxiang Xu, Wen Chen

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.4, pp. 77-77, 2019, DOI:10.32604/icces.2019.05090

    Abstract Creep of concrete can last for decades, which displays the ultra-slow rheological phenomena. As an empirical formula, the logarithmic law is usually used to describe the ultra-slow creep. However, the logarithmic law does not always work well especially for the long-term creep. And its corresponding relaxation response cannot be obtained analytically. It is known that the Mittag-Leffler and the inverse Mittag-Leffler functions are generalized from the exponential and the logarithmic functions, respectively. And the inverse Mittag-Leffler function is much slower and generalized than the logarithmic function. In this paper, we use the non-local structural derivative to establish a new Maxwell-type… More >

  • Open Access


    Experimental Study on CT Micro Mechanics Characteristics of Soft Rock Creep under Gravity Disturbance Loads

    FU Zhiliang1, GUO Hua2, GAO Yanfa3

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.5, No.3, pp. 145-156, 2008, DOI:10.3970/icces.2008.005.145

    Abstract This paper is focused on the micro-damage evolution properties of gray green mudstone under impacting disturbance load conditions for the first time by using the real time CT testing technique. CT images and CT values for rock cross-sections under different impacting disturbance loading levels were obtained. The paper is also to describe process of rock creep damage under disturbance loads and to explore the mechanism of micro-damage. The results have shown that rock failure is easy to happen suddenly rock is in or close to limit strength neighborhood during the process of disturbance. This will further lay the theory basis… More >

  • Open Access


    Shape-Effect in the Effective Laws of Plain and Rubberized Concrete

    E. Ferretti

    CMC-Computers, Materials & Continua, Vol.30, No.3, pp. 237-284, 2012, DOI:10.3970/cmc.2012.030.237

    Abstract The procedure of the effective law outlined in this paper [Ferretti (2001); Ferretti and Di Leo (2003); Ferretti (2004b)] is an experimental procedure for identifying the constitutive law in uniaxial compression of brittle heterogeneous materials, and is based on the physical, analytical and numerical discussions about the existence or otherwise of strain-softening [Ferretti (2004a); Ferretti (2005)]. This procedure allows us to correct several incongruities that characterize the average stress versus average strain diagrams: it produces evidence against strain-softening in uniaxial compression [Ferretti (2004b)], whose existence may be questioned from a physical point of view [Ferretti (2004a); Ferretti (2005)], it provides… More >

  • Open Access


    Axisymmetric Slow Motion of a Prolate Particle in a Circular Capillary with Slip Surfaces

    Hong Y. Yeh, Huan J. Keh1, *

    CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.3, pp. 343-366, 2017, DOI:10.3970/cmes.2017.113.361

    Abstract The problem of the steady migration of an axially symmetric prolate particle along its axis of revolution coinciding with the centerline of a circular capillary is investigated semi-analytically in the limit of low Reynolds number, where the viscous fluid may slip at the solid surfaces. A method of distribution of spherical singularities along the axis inside the particle is employed to establish the general solution of the fluid velocity satisfying the boundary conditions at the capillary wall and infinity. The slip condition at the particle surface is then satisfied by using a boundary collocation method to determine the unknown constants… More >

  • Open Access


    Long-term Analyses of Concrete-Filled Steel Tubular Arches Accounting for Interval Uncertainty

    Yong-Lin Pi1, Mark Andrew Bradford1

    CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.3, pp. 233-253, 2014, DOI:10.3970/cmes.2014.099.233

    Abstract Creep and shrinkage of the concrete core of a concrete-filled steel tubular (CFST) arch under sustained loading are inevitable, and cause a long-term change of the equilibrium configuration of the CFST arch. As the equilibrium configuration changes continuously, the long-term radial and axial displacements of the CFST arch, stress distributions as well as the internal forces in the steel tube and the concrete core change substantially with time. Creep and shrinkage of the concrete core are related to a number of its material parameters such as its creep coefficient, aging coefficient, and shrinkage strain. The values of these parameters differ… More >

  • Open Access


    Creep of Concrete Core and Time-Dependent Non-Linear Behaviour and Buckling of Shallow Concrete-Filled Steel Tubular Arches

    K. Luo1, Y. L. Pi1, W. Gao1, M. A. Bradford1

    CMES-Computer Modeling in Engineering & Sciences, Vol.95, No.1, pp. 31-58, 2013, DOI:10.3970/cmes.2013.095.031

    Abstract This paper presents a theoretical analysis for the time-dependent nonlinear behaviour and buckling of shallow concrete-filled steel tubular (CFST) arches under a sustained central concentrated load. The virtual work method is used to establish the differential equations of equilibrium for the time-dependent behaviour and buckling analyses of shallow CFST arches, and the age-adjusted effective modulus method is adopted to model the creep behaviour of the concrete core. Analytical solutions of time-dependent displacements and internal forces of shallow CFST arches are derived. It has been found that under a sustained central concentrated load, the deformations and bending moments in a shallow… More >

  • Open Access


    Thermocapillary Motion of a Spherical Drop in a Spherical Cavity

    Tai C. Lee1, Huan J. Keh2

    CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.5, pp. 317-333, 2013, DOI:10.3970/cmes.2013.093.317

    Abstract A theoretical study of the thermocapillary migration of a fluid sphere located at an arbitrary position inside a spherical cavity is presented in the quasisteady limit of small Reynolds and Marangoni numbers. The applied temperature gradient is perpendicular to the line through the drop and cavity centers. The general solutions to the energy and momentum equations governing the system are constructed from the superposition of their fundamental solutions in the spherical coordinates originating from the two centers, and the boundary conditions are satisfied by a multipole collocation method. Results for the thermocapillary migration velocity of the drop are obtained for… More >

  • Open Access


    Numerical Investigation of Creep Damage Development in the Ni-Based Superalloy IN738 LC at 850 °C

    Wolfgang Brocks1, Weidong Qi2

    CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 313-320, 2002, DOI:10.3970/cmes.2002.003.313

    Abstract Results of a numerical study of creep damage development and its effect on the deformation behavior in the Ni-based superalloy IN 738 LC at 850 °C are reported. A continuum damage mechanics based anisotropic damage model has been coupled with the unified model of Chaboche, and is used for the present study. Numerical computations are performed on a plate containing a circular hole under tension. They show that the applied damage model does not cause damage localization and no significant mesh-dependence of the results are observed. More >

  • Open Access


    Slow Rotation of an Axially Symmetric Particle about Its Axis of Revolution Normal to One or Two Plane Walls

    Yi W. Wan1, Huan J. Keh2

    CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 109-138, 2011, DOI:10.3970/cmes.2011.074.109

    Abstract The steady rotation of an axially symmetric particle about its axis of revolution normal to two plane walls at an arbitrary position between them in a viscous fluid is studied theoretically in the limit of small Reynolds number. The fluid is allowed to slip at the surface of the particle. A method of distribution of a set of spherical singularities along the axis of revolution inside a prolate particle or on the fundamental disk within an oblate particle is used to find the general solution for the fluid velocity distribution that satisfies the boundary conditions at the confining walls and… More >

  • Open Access


    Size-Dependent Behavior of Macromolecular solids II: Higher-Order Viscoelastic Theory and Experiments

    D. C. C. Lam1, L-H Keung1, P. Tong2

    CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.1, pp. 73-100, 2010, DOI:10.3970/cmes.2010.066.073

    Abstract Additional molecular rotations in long chained macromolecules lead to additional size dependence. In this investigation, we developed the higher order viscoelasticity framework and conducted experiments to determine the higher order material length scale parameters needed to describe the higher order viscoelastic behavior in the new framework. In the first part of the investigation of high order deformation behavior of macromolecular solids, the higher-order viscoelasticity theories for Maxwell and Kelvin-Voigt materials, and models of higher-order viscoelastic beam deflection creep are developed in this study. We conducted creep bending experiments with epoxy beams to show that the creep deflection behavior followed the… More >

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